1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device in which a central processing unit (CPU) or a logic circuit, and direct random access memory (DRAM) are mounted on a semiconductor chip, and, more particularly, to a semiconductor integrated circuit device capable of performing burn-in test efficiently, in which a central processing unit (CPU) or a logic circuit, and dynamic random access memory (DRAM) are mounted on a semiconductor chip.
2. Description of the Prior Art
FIG. 6 is a block diagram showing a configuration of a conventional semiconductor integrated circuit device on a semiconductor chip 1 on which a dynamic random access memory (DRAM) is mounted. In FIG. 6, the reference number 1 designates a semiconductor chip, 2 denotes a dynamic random access memory (DRAM) mounted on the semiconductor chip 1, 3 indicates an external terminal group having a plurality of external terminals through which burn-in test patterns are provided from external devices (not shown) to the semiconductor chip 1 and the burn-in test patterns are used for operation test of the DRAM 2. The reference number 4 designates a wiring group having a plurality of lines through which the received burn-in test patterns are transferred to the DRAM 2. The reference number 5 denotes input terminal group having a plurality of input terminals of the DRAM 2. Further, input/output buffers (I/O buffers that are omitted from FIG. 6) whose number is corresponding to the number of the external terminals in the external terminal group 3 are formed in the semiconductor chip 1.
FIG. 7 is a block diagram showing a configuration of another conventional semiconductor integrated circuit device formed on a semiconductor chip 1 on which a central processing unit (CPU) or a logic circuit and a DRAM are mounted. The reference number 6 designates the CPU or the logic circuit and 2 indicates the DRAM. The reference number 7 indicates a wiring group having a plurality of lines through which the CPU or the logic circuit 6 and the DRAM 2 are connected.
Next, a description will be given of the operation of the semiconductor integrated circuit device shown in FIG. 6.
In general, a burn-in test for the DRAM 2 is the test of a reliability performance measurement in order to detect a life time of the DRAM 2. When the burn-in test for the DRAM 2 in the configuration of the semiconductor chip 1 shown in FIG. 6 is performed, burn-in test patterns are inputted through the external terminal group 3 and the I/O buffers (not shown) in the semiconductor chip 1, and then the received burn-in test patterns are transferred to the input terminal group 5 of the DRAM 2 through the wiring group 4.
In the conventional semiconductor integrated circuit device shown in FIG. 6, after the burn-in test patterns are provided to the DRAM 2, test results obtained from the DRAM 2 are transferred to external devices through the external terminal group 3 and then the test results are compared with the burn-in test patterns in order to perform the reliability test of the operation of the DRAM 2.
FIG. 7 shows the configuration of the conventional semiconductor integrated circuit device of a hybrid type in which both the CPU or the logic circuit 6 and the DRAM 2 are mounted on the same semiconductor chip 1. This hybrid type semiconductor device is becoming one of the leading mainstreams of large scale hybrid integrated semiconductor circuit devices. By using the configuration of the semiconductor integrated circuit device shown in FIG. 7, it is possible to avoid a drawback caused in the configuration of an interface between a chip of the CPU or the logic circuit 6 and a chip of the DRAM 2. On the contrary, the configuration shown in FIG. 7 has the wiring group 4 having a plurality of lines through which the CPU or the logic circuit 6 are connected to the DRAM 2 electrically. In the prior art, when the burn-in test for the DRAM 2 is performed in the configuration shown in FIG. 7, there is a drawback that it is difficult to input burn-in test patterns directly to the DRAM 2 through an external terminal group and corresponding I/O buffers (omitted from FIG. 7) and difficult to perform the burn-in test for the DRAM 2 correctly.
As described above, because the conventional semiconductor integrated circuit device has the configuration shown in FIG. 6 in which only the DRAM 2 is formed on the semiconductor chip 1, when the burn-in test is performed, it must be required to have the external terminal group 3, the I/O buffers, and the lines forming the wiring group 4 whose number is corresponding to the number of the input terminals of the DRAM 2. Accordingly, there is a case that it is difficult to form the dedicated terminals for the burn-in test pattern in the semiconductor chip in configuration.
In addition, according to the development of large scale integrated circuit devices as DRAM 2, it must be required to form a plurality of dedicated terminals in the external terminal group 3 and I/O buffers only for the test of the DRAM 2 under the limitation of the number of the terminals in the external terminal group 3 and the I/O buffers in the semiconductor chip 1. In addition to this drawback, in the prior art, there is another drawback that the wiring group 4 requires a larger area in the semiconductor chip 1 under the limitation of the area of the semiconductor chip 1. Furthermore, because the burn-in test is the reliability test only for the DRAM 2, not for the CPU, the logic circuit, and the wiring group as component elements other than the DRAM 2 mounted on the same semiconductor chip 1, it is required to minimize the number of the component elements other than the DRAM 2. However, a plurality of I/O buffers are formed corresponding to the number of the terminals in the external terminal group 3, and operate. This causes to add the influence of the defects of the component elements, such as the I/O buffers, other than the DRAM 2 into the test result of the burn-in test only for the DRAM 2. Thereby, this causes to decrease the accuracy of the reliability of the test result of the burn-in test for the DRAM 2.
Moreover, the wiring group 7 having a plurality of lines is formed between the CPU or the logic circuit 6 and the DRAM 2 in the conventional hybrid type semiconductor integrated circuit device shown in FIG. 7 in which the CPU or the logic circuit 6 and the DRAM 2 are mounted on the same semiconductor chip 1. Accordingly, there is the drawback that when the burn-in test for the DRAM 2 is performed, it is difficult to input burn-in test patterns directly to the DRAM 2 through external terminals and corresponding I/O buffers (omitted from FIG. 7) and it is also difficult to perform the burn-in test for the DRAM 2 correctly.
Accordingly, an object of the present invention is, with due consideration of the drawbacks of the conventional semiconductor integrated circuit device, to provide a semiconductor integrated circuit device as a hybrid type semiconductor integrated circuit device, in which a CPU or a logic circuit and a DRAM are mounted on a same semiconductor chip, capable of performing a burn-in test for the DRAM without increasing the number of external terminals, I/O buffers, and wiring group in the semiconductor chip.
In accordance with a preferred embodiment of the present invention, a semiconductor integrated circuit device comprises a central processing unit (CPU) or a logic circuit mounted on a same semiconductor chip, a dynamic random access memory (DRAM) mounted on the same semiconductor chip, and a pattern generator for generating burn-in test patterns for the DRAM based on control signals received through external terminals of the same semiconductor chip and for providing the generated burn-in test patterns to input terminals of the DRAM. In the semiconductor integrated circuit device described above, the number of the input terminals of the DRAM is greater than the number of the external terminals of the same semiconductor chip.
The semiconductor integrated circuit device as another preferred embodiment according to the present invention, further comprises a switch circuit for switching a first wiring group through which the burn-in test patterns generated by the pattern generator are transferred to the input terminals of the DRAM and a second wiring group through which data items are transferred from the CPU or the logic circuit to the DRAM, and for connectingly switched one in the first wiring group and the second wiring group to the input terminals of the DRAM.
In accordance with another preferred embodiment of the present invention, a semiconductor integrated circuit device comprises a central processing unit (CPU) or a logic circuit mounted on a same semiconductor chip, a dynamic random access memory (DRAM) mounted on the same semiconductor chip, and a pattern generator, formed in the CPU or the logic circuit, for generating burn-in test patterns for the DRAM based on control signals received through external terminals of the same semiconductor chip and for providing the generated burn-in test patterns to input terminals of the DRAM. In the semiconductor integrated circuit device described above, the number of the input terminals of the DRAM is greater than the number of the external terminals of the same semiconductor chip.
In the semiconductor integrated circuit device as another preferred embodiment according to the present invention, a wiring group through which the burn-in test patterns are transferred from the pattern generator to the input terminals of the DRAM is commonly used during a normal operation other than a burn-in test operation in which data items are transferred to the CPU or the logic circuit to the input terminals of the DRAM.
In the semiconductor integrated circuit device as another preferred embodiment according to the present invention, the switch circuit is a selector group comprising a plurality of selectors for switching the first wiring group through which the burn-in test patterns generated by the pattern generator are transferred to the input terminals of the DRAM and the second wiring group through which data items are transferred from the CPU or the logic circuit to the DRAM, and for connectingly switched one in the first wiring group and the second wiring group to the input terminals of the DRAM.